local function add_two_numbers(number_one, number_two) -- Function means the following is a function definition.
													   -- add_two_numbers is the function name.
													   -- number_one and number_two are arguments.

  local number_three = number_one + number_two		   -- Sets number_three variable to the value of number_one plus number_two
  return number_three								   -- Returns the value behind the return to the calling code.

end 												   -- You need to close the function with end keyword.

print(add_two_numbers(5, 2)) -- Prints 7.